Air conditioning system



Jan. 18, 1955 .IERBS 2,699,922

\ AIR CONDITIONING SYSTEM Filed June 23, 1951 2 Sheets-Sheet l Pigl.

b flmMdLW/ I.

His Attorney.

1955 R. s. HERBST 2,699,922

AIR CONDITIONING SYSTEM Filed June 23, 1951 2 Sheets-Sheet 2 Inventor:Robewt S. Her-bat,

is Attorney.

United States "we AIR CONDITIONING SYSTEM Robert S. Herbst, East Orange,N. J., assignor to General 7 This invention relates to air conditioningsystems and particularly to such systems which provide both heating andcooling and are employed for maintaining required temperature conditionsthroughout the year.

In air conditioning systems, such as warm air systems for heatingresidences, cooling for summer operation may be provided by connecting acooling unit to the same room air supply system. It is desirable thateither the heating system or the cooling system may be employed withoutrequiring complicated changeover operation. Furthermore, when bothheating and cooling are supplied for residential air conditioning, it isdesirable that the entire operation of changing over from summerconditioning to winter conditioning be made without requiring specialtools or special knowledge of the system. Accordingly, it is an objectof this invention to provide in an air conditioning system a simple andeffective control for changing from heating to cooling operationincluding an improved arrangement for changing the air circulatingpaths. It is another object of this invention to provide an airconditioning unit including a blower and heat transfer surface and animproved automatic air circuit control dependent upon the operation ofthe unit blower.

Further objects and advantages of the invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaim annexed to and forming a part of this specification.

In carrying out the objects of this invention an air conditioning systemincluding a warm air heating unit and an air cooling unit is arrangedwith a common duct for supplying conditioned air to an enclosure. Thetwo units are arranged to be operated alternatively and may be connectedeither in series or in parallel in the air circuit. In either case, anautomatic damper of the check valve type is provided to allow a flow ofair through the outlet of the cooling unit whenever the cooling bloweris in operation but to prevent such flow whenever the heating unit is inoperation. When the two units are arranged to be connected in series,the heating unit outlet supplies air to the inlet of the cooling unit,and the automatic damper is so arranged that the blower and heattransfer surface of the cooling unit are by-passed during heatingoperation; however, during cooling operation both the heating andcooling blowers may be employed to circulate air in series, therebyproviding a boosting effect for summer air conditioning.

For a better understanding of this invention, reference may be had tothe accompanying drawings in which Fig. l is a diagrammatic illustrationof an air conditioning system for summer and winter operation embodyingthe invention, and Fig. 2 is a diagrammatic illustration of a similarheating and cooling air conditioning system embodying a modified form ofthe invention.

Referring now to the drawing, the air conditioning system illustrated inFig. 1 comprises a warm air heating furnace or similar unit 10 and anair cooling unit 11 connected to deliver air through a duct 12 to a roomwithin an enclosure indicated generally by the dot and dash lines. Theair is returned from the room for recirculation through the airconditioning system by a duct 13. The heating unit comprises a casing 14within which is arranged a combustion chamber 15 provided with a fuelburner 16 which may, for example, be a gas burner actuated in accordancewith operation of a suitable supply or control unit 17. Combustion airfor the burner 16 is supplied through a suitable duct structure (not2,699,922 Patented Jan. 18,1955

shown) and the products of combustion rise through the" chamber 15 tothe top of the casing and are removed through a stack connection 18. Anormally closed" damper 19 is mounted in the connection 18 and is conftrolled to be opened whenever the furnace is'in operation.- The productsof combustion rising from chamber 15 pass around heat transfer tubes 20through which the air tof be heated is circulated by operation of ablower 21 driven'-" by an electric motor 22. The air is admitted totheblower through an inlet duct'23 providing communication be tween thereturn air duct 13 and the blower, and the air, after being heated bypassage through the tubes 20,-'isf conducted upwardly through a forwardmanifold'passage 24 and passes through a duct 25 to the bottom of thesupply duct 12. I The cooling unit 11 comprises a casing 27 divide'dintoa refrigerating machinecompartment 28 and a blower compartment 29.Within the blower compartment 29" are arranged a heat transfer surface30, which may be the evaporator of a refrigerating machine, and a blower31 driven by an electricmotor 32 for circulating air over the heattransfer surface 30. In the compartment 28 is arranged a compressiontype refrigerating machine driven by an electric motor 33 and includinga refrigerant compressor and condenser (not shown), the compressor beingdriven by the motor 33 through a belt 34 in. the usual manner. When theblower 31 is in operation, air is drawn from the return duct 13 throughan inlet connection 35 and thence flows to the blower through a passage36 and a by-pass 37, a pivotally mounted damper 38 I being biased to itsopen position through its connecting rod 39 and a compression spring 40.At least a portion of the air, therefore, thus flows over the heattransfer 2 surface 30 and is delivered to the supply duct 12 to adischarge conduit 41. Under conditions of operation re-' quiring thefull cooling capacity of the unit 11,. the? damper 38 is operated toclose the passage 37 so thatthe entire air stream is circulated over theheat transfersurface. The selection of the heating or coolingoperationis, effected by operation of a selector switch and thermo-- staticcontrol 42. When it is desired to operate the'fur' nace, a manual switch43 is moved to engage-its lefthand contact indicated at 44 andthereby-connect a thermostat represented as a bimetallic strip 45 incircuit; with the secondary coil of a transformer 46. Thetranjsformer isconnected across electric supply lines 47. The control 42 is arrangedwithin the space to be conditioned, J and when there is a decrease intemperature sufiicientto create a demand for heating, the element45'moves to the right to engage its stationary contact indicated at 48and thereby connects the electric control of the unit 17 and a solenoidcoil 49 in parallel across the secondaryof-tllf transformer 46.Energization of the coil 49 lifts an armature 50 and moves the damper 19to its open position. Energization of the control 17 ignites the burner,16, and as soon as the temperature reaches a prdetermined value withinthe casing 14, as determined by a bimetallic thermostat 52 mounted inthe manifold 24, the element moves to the left engaging its stationarycontact 53 and connects the motor 22 to the supply lines 47 through alead 54, a connection 55 and a lead'56. The blower is continued inoperation as long as the tempera ture in the manifold 24 remains abovethe predetermined"; value. The heated air is then circulated bytheblo'wer' 21 through the tubes 20 and out the duct 25 to the supplyduct 12. An automatic damper 57 is provided in the duct 25 and is openedby the pressure of the air s1'1'pplied upon operation of the fan 21.This damper is of v the check type and prevents reverse flow through theduct. 25, the upper portion of the damper striking a stop- 58 when thedamper moves in a clockwise direction to its closed position as shown. 1

When it is desired to operate the air conditioning-systern for supplyingcooling air to the enclosure, the switch 43 of the control 42 is movedto the right toengageits right-hand contact indicated at 60 andthereby'conn'ects 1 two bimetallic thermostatstrips 61 and 62.to the.second-1. ary of the transformer 46. When the temperature in the room tobe conditioned reaches a predetermined value constituting a demand forcooling, the strip 61 moves to 3 the rightand engagesa stationarycontact 63, thereby connecting a coil 64 of a relay 65 across thesecondary of the transformer. This energizes the relay, thereby closingit to connect a lead 66 of the cooling unit to the supply lead 56. Themotors 32 and 33 are thus connected in parallel across the supply line47 and operation of the cooling unit is initiated, air being circulatedthrough the casing 27 and a portion of it over the heat transfer surface30, the conditioned air and by-passed air entering the blower 31' andbeing discharged through the duct 41 to the supply duct 12. An automaticdamper 68 is pivotally mounted in the connection 41 and is opened by theforce of air discharged from the blower 31;. When the blower 31 is notinoperation, the damper 68 returns in a-counterclockwise direction untilits upper portion engages a stop 69.,

Should, the temperature within the enclosure continue to rise,th,esecond bimetallic element 62 will move to the right sufficiently toengage a stationary contact 76 and thereby connect a coil 71 across thesecondary of the transformer. When the coil 71 is'energized in thismanner, it' attracts an armature 72 attached to the operating rod 39 ofthe damper 38 and moves the rod to the right in opposition to the spring40', thereby closing the damper 38: The entire stream of air receivedfrom the inlet 35 isthen'circulated by the blower 31 over the heattransfer surface 30 and the maximum cooling capacity of the unit isrealized.

Should the cooling demand be met, the thermostat 62 willopen leaving thecooling unit in operation with the by-pass' 37' open until thethermostatic element 61. has been satisfied by further reduction intemperature whereupon operation of the'unit 11 is suspended, the coil 64being deenergized and the relay 65 opened.

The dampers 57 and 68 prevent reverse flow of air through theirrespective conduits 25 and 41. Thus, cooled air is not lost through thewarm air conditioner 10, and during the heating season hot air is notlost through the cooling unit 11. This latter feature is particularlydesirable in order to prevent heating of the refrigerant in the heattransfer surface 30. These automatic dampers require no attention fromthe user, it being unnecessary to change damper connections by hand, andfurthermore these dampers are simple in their automatic operation and donot require the addition of complicated controls or other devices. Theoperation of the heating and cooling units is thus coordinated in amanner such that they may be employed effectively without interferencebecause of their connectio'n'to a common air circulating system.

The air conditioning system illustrated in Fig. 2 is similar to thatshown in'Fig. 1 but includes structural changes in the cooling unit andcorresponding parts of which have been designated by the same numeralsas in Fig. 1' with the addition of the letter a. This system differsfrom that of Fig. 1 in that'the heating and cooling units are providedwith air ducts such that they may be connected in series in the path ofair flow so that the two fans or blowers may be operated together toprovide a boosting effect. The cooling unit indicated at 11a differsfrom the cooling unit 11 of Fig. 1 in that a single automatic damper isincorporated therein which takes the place of both' dampers 57 and 630iFig. 1. As shown inthe drawing, the-cooling unit 11a comprises a casingq 27a having'a -blower compartment or chamber 29a intermediate amachinery compartment 28a and a plenum chamber 75 at the top of theunit. The heating unit isfprovided with a lateral outlet 76 instead ofthe vertical outlet 250i Fig. 1 but is otherwise of the sameconstruction in both figures. The outlet 76 is connected directly to theinlet of the unit 11a as indicated at '77 so that the air dischargedfrom the heating unit it) enters the left end of the plenum chamber 75.In order to control automatically the passages through which air flowsin the heating and cooling operations, a damper 78 is pivotally mountedon a transverse axis intermediate an intake opening 79 of the blowerchamber 29a and the discharge opening of a blower 31a as indicated at80. The damper includes an upper portion 81 which, in the positionshown, operates the inlet and outlet of the plenum chamber 25 anddirects the air downwardly into the chamber 29a. A lower portion 82 ofthe damper in the position shown lies Within the inlet 79. The damper isbiased to its vertical position by gravity action through a laterallyoffset weight 83. When the blower 31a is not in operation and the blower21 is started and discharges air from the heating unit it the damper 78is moved by the air pressure and rotates in a clockwise direction to thedotted line position wherein it closes the inlet 79 and the outlet 80 ofthe blower chamber and prevents the back flow of the air into the blowerchamber and thence about the heat transfer surface indicated at 30a.Also in the dotted line position, the weight 33 lies on the right-handside of the axis of the damper and biases the damper to its dotted lineposition.

When the damper is in the dotted line position and the blower 31a isplaced in operation, the damper is moved by the force of the airdischarged by the blower and returned to its vertical position as shownon the drawing. Thus whenever the cooling unit is in operation theblower is in' the full line position shown in the drawing.

The control of the system in Fig. 2 is essentially the same as that ofFig. 1 except that a second switch element indicated at 84 is providedon the relay 65a so that when the thermostat 61 calls for cooling, theswitch 84 closes a circuit frorn'the line 56 through a lead 85 to themotor 22. Thus during the cooling operation both blowers are energizedand air is circulated from the heating unit 10 through the duct 76 andinto the blower chamber of the unit 11a through the intake 79 and thencethrough the blower 31a to the outlet duct indicated at 12a. The twofans, therefore, operate in tandem, the fan 21 providing a boosteraction for the fan 3111. This general arrangement of the fans for thecooling operation is described and broadly claimed in an application ofSamuel J. Levine, Serial No. 119,676, filed October 5, 1949 (now PatentNo. 2,498,397), and assigned to the same assignee as the presentinvention.

It is evident that in the arrangement of Fig. 2 the automatic damper 81assures operation of the air ducts to positively direct the air in therequired direction under both heating and cooling conditions, and thesystem performs all its functions for either heating or cooling uponselection of either condition by movement of the manual switch 43 of thecontrol 42.

Although this invention has been described in connection with particularair conditioning systems, other applications will readily be apparent tothose skilled in the art. limited to the specific arrangementsillustrated and described and it is intended by the appended claim tocover all modifications within the spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

An air conditioning system for heating and cooling the air in anenclosure comprising an air heating unit and an air cooling unit, eachof said units including a heat transfer surface and a blower forcirculating air thereover and for discharging the conditioned air fromthe unit, an outlet conduit, an outlet duct for each of said units forconducting air discharged from the respective units to said outletconduit, automatic check dampers for preventing reverse flow of air inboth said ducts, the check damper in one of said ducts being biased to aclosed position by the force of air discharged from the other of saidducts, and means for selectively and alternatively operating said unitsto actuate their respective blowers and heat transfer units.

References Cited in the file of this patent UNITED STATES PATENTS152,031 Baker June 16, 1874 843,909 Peters Feb. 12, 1907 2,011,787Whiteley Aug. 20, 1935 2,551,956 Lund May 8, 1951 2,598,397 Levine May27, 1952 2,600,842 Buecken June 17, 1952 FOREIGN PATENTS 12,467 GreatBritain May 23, 1910 It is not, therefore, desired that the invention be

